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This commit is contained in:
Pavel Kartavyy 2015-10-14 14:58:16 +03:00
commit 3069d6fe8f
4 changed files with 1000147 additions and 37 deletions
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123
dbms/include/DB/IO/ReadHelpers.h
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@ -112,6 +112,11 @@ inline void assertString(const String & s, ReadBuffer & buf)
assertString(s.c_str(), buf);
}
bool checkString(const char * s, ReadBuffer & buf);
inline bool checkString(const String & s, ReadBuffer & buf)
{
return checkString(s.c_str(), buf);
}
inline void readBoolText(bool & x, ReadBuffer & buf)
{
@ -120,14 +125,20 @@ inline void readBoolText(bool & x, ReadBuffer & buf)
x = tmp != '0';
}
template <typename T>
void readIntText(T & x, ReadBuffer & buf)
template <typename T, typename ReturnType = void>
ReturnType readIntTextImpl(T & x, ReadBuffer & buf)
{
static constexpr bool throw_exception = std::is_same<ReturnType, void>::value;
bool negative = false;
x = 0;
if (buf.eof())
{
if (throw_exception)
throwReadAfterEOF();
else
return ReturnType(false);
}
while (!buf.eof())
{
@ -139,7 +150,7 @@ void readIntText(T & x, ReadBuffer & buf)
if (std::is_signed<T>::value)
negative = true;
else
return;
return ReturnType(false);
break;
case '0':
case '1':
@ -157,14 +168,27 @@ void readIntText(T & x, ReadBuffer & buf)
default:
if (negative)
x = -x;
return;
return ReturnType(true);
}
++buf.position();
}
if (negative)
x = -x;
return ReturnType(true);
}
template <typename T>
void readIntText(T & x, ReadBuffer & buf)
{
readIntTextImpl<T, void>(x, buf);
}
template <typename T>
bool tryReadIntText(T & x, ReadBuffer & buf)
{
return readIntTextImpl<T, bool>(x, buf);
}
/** Более оптимизированная версия (примерно в 1.5 раза на реальных данных).
* Отличается тем, что:
@ -211,18 +235,53 @@ void readIntTextUnsafe(T & x, ReadBuffer & buf)
x = -x;
}
template <bool throw_exception, class ExcepFun, class NoExcepFun, class... Args>
bool exceptionPolicySelector(ExcepFun && excep_f, NoExcepFun && no_excep_f, Args &&... args)
{
if (throw_exception)
{
excep_f(std::forward<Args>(args)...);
return true;
}
else
return no_excep_f(std::forward<Args>(args)...);
};
/// грубо
template <typename T>
void readFloatText(T & x, ReadBuffer & buf)
template <typename T, typename ReturnType>
ReturnType readFloatTextImpl(T & x, ReadBuffer & buf)
{
static constexpr bool throw_exception = std::is_same<ReturnType, void>::value;
bool negative = false;
x = 0;
bool after_point = false;
double power_of_ten = 1;
if (buf.eof())
{
if (throw_exception)
throwReadAfterEOF();
else
return ReturnType(false);
}
auto parse_special_value = [&buf, &x, &negative](const char * str, T value)
{
auto assert_str_lambda = [](const char * str, ReadBuffer & buf){ assertString(str, buf); };
auto check_str_lambda = [](const char * str, ReadBuffer & buf){ return checkString(str, buf); };
++buf.position();
bool result = exceptionPolicySelector<throw_exception>(assert_str_lambda, check_str_lambda, str, buf);
if (result)
{
x = value;
if (negative)
x = -x;
}
return result;
};
while (!buf.eof())
{
@ -262,47 +321,51 @@ void readFloatText(T & x, ReadBuffer & buf)
{
++buf.position();
Int32 exponent = 0;
readIntText(exponent, buf);
bool res = exceptionPolicySelector<throw_exception>(readIntText<Int32>, tryReadIntText<Int32>, exponent, buf);
if (res)
{
x *= exp10(exponent);
if (negative)
x = -x;
return;
}
return ReturnType(res);
}
case 'i':
++buf.position();
assertString("nf", buf);
x = std::numeric_limits<T>::infinity();
if (negative)
x = -x;
return;
return ReturnType(parse_special_value("nf", std::numeric_limits<T>::infinity()));
case 'I':
++buf.position();
assertString("NF", buf);
x = std::numeric_limits<T>::infinity();
if (negative)
x = -x;
return;
return ReturnType(parse_special_value("NF", std::numeric_limits<T>::infinity()));
case 'n':
++buf.position();
assertString("an", buf);
x = std::numeric_limits<T>::quiet_NaN();
return;
return ReturnType(parse_special_value("an", std::numeric_limits<T>::quiet_NaN()));
case 'N':
++buf.position();
assertString("AN", buf);
x = std::numeric_limits<T>::quiet_NaN();
return;
return ReturnType(parse_special_value("AN", std::numeric_limits<T>::quiet_NaN()));
default:
if (negative)
x = -x;
return;
return ReturnType(true);
}
++buf.position();
}
if (negative)
x = -x;
return ReturnType(true);
}
template <class T>
inline bool tryReadFloatText(T & x, ReadBuffer & buf)
{
return readFloatTextImpl<T, bool>(x, buf);
}
template <class T>
inline void readFloatText(T & x, ReadBuffer & buf)
{
readFloatTextImpl<T, void>(x, buf);
}
/// грубо; всё до '\n' или '\t'
void readString(String & s, ReadBuffer & buf);

11
dbms/src/IO/ReadHelpers.cpp
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@ -26,14 +26,21 @@ static void __attribute__((__noinline__)) throwAtAssertionFailed(const char * s,
}
void assertString(const char * s, ReadBuffer & buf)
bool checkString(const char * s, ReadBuffer & buf)
{
for (; *s; ++s)
{
if (buf.eof() || *buf.position() != *s)
throwAtAssertionFailed(s, buf);
return false;
++buf.position();
}
return true;
}
void assertString(const char * s, ReadBuffer & buf)
{
if (!checkString(s, buf))
throwAtAssertionFailed(s, buf);
}
void assertChar(char symbol, ReadBuffer & buf)

1000000
dbms/src/IO/tests/DevicePixelRatio Normal file
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File diff suppressed because it is too large Load Diff

40
dbms/src/IO/tests/read_float_perf.cpp Normal file
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@ -0,0 +1,40 @@
#include <string>
#include <iostream>
#include <fstream>
#include <DB/Core/Types.h>
#include <DB/IO/ReadHelpers.h>
#include <DB/IO/ReadBufferFromIStream.h>
#include <DB/IO/CompressedReadBuffer.h>
int main(int argc, char ** argv)
{
try
{
std::ifstream istr("DevicePixelRatio");
DB::ReadBufferFromIStream in(istr);
DB::Float32 b = 0;
size_t i = 0;
while (!in.eof())
{
DB::readFloatText(b, in);
in.ignore();
++i;
}
std::cout << b << std::endl;
std::cout << i << std::endl;
}
catch (const DB::Exception & e)
{
std::cerr << e.what() << ", " << e.displayText() << std::endl;
return 1;
}
return 0;
}